Hi Robo,
God yes!. of course we want to see your VCF1 layout. I got this design onto a credit card sized piece of stripboard. so cool to see another persons parts placement decisions tho. This is a classic filter and quite steiner like.

ok, so here's the stuff.
it's one of my first *proper* pcbs ...
it's unbuilt and untested. and it'll be a month from now until i really get to this. i crammed the stuff a bit inone corner so that the layout fits the usual 100mm of pcb material.
i double checked it, so everything should be ok.
i quite convinced that it'll work properly.
would be glad if someone could do the triple check, though...

ah - it's designed for discrete matched transistors.

as far as i searched the web, i couldn't find anyone doing or selling pcbs for this, so i guess it's appreciated to post this.

i did the layout in expresspcb. it's freeware and i'd say it's only real downside is that you can't export gerber files - which is a big one but doesn't matter for me since i etch pcb's on my own.
When i was searching for free pcb-layout-editors this was the one i felt really comfortable with. very nice workflow and intuitive handling.
i attached the .pcb (expresspcb) file in the .zip folder, so one can make changes to the layout if one needs to.

Thanks also for the link to the stripboard layout, nardu!
i always preferred perfboards and never felt comfortable with strip boards.
(i guess it's a what you grew up with thing )
but surely it's really good to have the link here. Also because of the LM13700 version!
Do you know if it sounds/behaves different to the CA3080 version?

i did the layout in expresspcb. it's freeware and i'd say it's only real downside is that you can't export gerber files - which is a big one but doesn't matter for me since i etch pcb's on my own.
When i was searching for free pcb-layout-editors this was the one i felt really comfortable with. very nice workflow and intuitive handling.
i attached the .pcb (expresspcb) file in the .zip folder, so one can make changes to the layout if one needs to.

Thanks also for the link to the stripboard layout, nardu!
i always preferred perfboards and never felt comfortable with strip boards.
(i guess it's a what you grew up with thing )
but surely it's really good to have the link here. Also because of the LM13700 version!
Do you know if it sounds/behaves different to the CA3080 version?

best wishes, rob

Hi rob
have you already build the filter with your pcb layout , will work ?

sorry for late reply, just came back from holidays
due to that, i still haven't built it. but it's one of those projects next in line, especially with forum motivation
yet, it's still too early for announcing a date or timeframe...

sorry for late reply, just came back from holidays
due to that, i still haven't built it. but it's one of those projects next in line, especially with forum motivation
yet, it's still too early for announcing a date or timeframe...

i'll post more when i get there.
best, r

hi rob thanks

i really want build the VCF-1 , unfortunately i'm not expert in electronic cad and pcb layout so any help is much apprecciate

i have try the adventure to build this stripboard , i realize that there is two time R5 resistor in the layout , and in the first power is burn the fuse -12V of my powersupply . i have chek 2 time the solders and jump seems all ok
boo

i wanted to confirm that the layout i posted is working. nicely
although the self resonance is quite harsh and dirty, not sure if this is the way it should be. i like it anyways.
no possibility for pics and sounds yet. these will follow.

i wanted to confirm that the layout i posted is working. nicely
although the self resonance is quite harsh and dirty, not sure if this is the way it should be. i like it anyways.
no possibility for pics and sounds yet. these will follow.

best, rob

good to hear it's working.

one thing i noticed on your layout is that the tempco is not mounted in thermal contact with transistor pair Q1/Q2. of course this has nothing to do with the resonance behaviour... regarding the sound - maybe you are overdriving the filter? what happens when you attenuate the input signal?

yeah... the tempco/transistor-pair position was a strange compromise.
i wanted to limit the size of the pcb in such a manner that one could fit three of them on a standard euro pcb (160mmx100mm) and i found no way manage to do it otherwise without starting from point one again.
anyway - it's totally possible to mount the tempco in contact and extend the wires to the other side of the op-amp, so i thought it's ok.

about the resonance issue - i'm talking only about self resonance - which occurs no matter if an input signal is present or not, so that's not the reason. i'm quite sure it's just the way it is.
i'll try to record a sound sample and post it here within the next week - it's way easier to talk about it then.

about the resonance issue - i'm talking only about self resonance - which occurs no matter if an input signal is present or not, so that's not the reason

oh, i see... sorry misread your post. so i guess it's not a clean sinewave but self-oscillation with harmonics..? my SEM VCF clone, which is rather similar to Thomas Henry's design does not self-oscillate, so i can't really comment on that.

sound samples would be cool!

PS: regarding your earlier question about the LM13700 - it's really the same thing as the CA3080, except for the addition of linearizing diodes and a buffer for each OTA... http://www.idea2ic.com/LM13700.html

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